1. Field of the Invention
The present invention relates to a color filter manufacturing method of applying a color filter material of a negative type onto a surface and carrying out an exposing treatment, a developing treatment and a heating treatment in this order, thereby forming a color filter.
2. Description of the Related Art
A color filter to be used in a solid-state image pick-up unit has generally been manufactured by a lithographic process (for example, JP-A-2000-122306).
FIGS. 5A to 5C are views for explaining a process for manufacturing a conventional color filter for a solid-state image pick-up unit. As shown in FIG. 5A, a coloring resist of a pigment dispersion type having a photosensitivity (a color filter material of a negative type) is applied onto a flattened film 100 to form a color filter material film and an exposing treatment is carried out by using a mask M having a predetermined pattern. As shown in FIG. 5B, next, a developing treatment for removing a portion other than the exposed portion is carried out. Next, a heating treatment for heating the color filter material film obtained after the developing treatment is executed to form a color filter having a predetermined pattern. By repetition of a serial process having the application of the color filter material film, the exposing treatment, the developing treatment and the heating treatment corresponding to a desirable number of colors in a color filter to be loaded onto a solid-state image pick-up unit, a color filter for a solid-state image pick-up unit having a desirable number of colors is manufactured.
In the exposing treatment, a portion on which a light is irradiated in a color filter material of a negative type causes a crosslinking reaction. In case of the color filter material of a negative type, however, a light transmittance is not very high. In a portion 101a which is close to the flattened film 100, therefore, the exposing treatment is ended without the generation of the crosslinking reaction. For this reason, in the case in which the heating treatment or a solvent treatment is carried out after the exposing and developing treatments, the portion 101a which is close to the flattened film 100 is deformed as shown in Fig. 5C. Therefore, it is hard to obtain a color filter taking a stable shape. When the color filter is deformed, there is a problem in that colors are mixed in the solid-state image pick-up unit, resulting in a deterioration in a performance.